Network Failure Detection Method and Network Failure Detection Device

1. A network failure detection method, comprising: capturing a plurality of packets; analyzing contents of the plurality of packets and detecting time to live values of the plurality of packets from the contents of the plurality of packets; determining whether a network failure occurs to generate a determination result according to the time to live values of the plurality of packets, the step comprising determining that the network failure occurs and generating the determination result when detecting that a time to live value of a first packet of the plurality of packets is not decreased sequentially; and outputting an alarm signal to implement an alarm function according to the determination result.

2. The network failure detection method of claim 1 , wherein the step of analyzing contents of the plurality of packets and determining whether the network failure occurs to generate the determination result according to the contents of the plurality of packets comprises: analyzing the contents of the plurality of packets and detecting whether the plurality of packets include more than one address of a dynamic host configuration protocol server; and when detecting that the plurality of packets include more than one address of the dynamic host configuration protocol server, determining that the network failure occurs and accordingly generating the determination result.

3. The network failure detection method of claim 2 , wherein the address of the dynamic host configuration protocol server is a physical address.

4. The network failure detection method of claim 1 , wherein the step of outputting the alarm signal to implement the alarm function according to the determination result comprises outputting the alarm signal to implement the alarm function when the determination result indicates that the network failure occurs.

5. A network failure detection device, comprising: a packet capture module configured to capture a plurality of packets; a packet filter module, coupled to the packet capture module and configured to analyze contents of the plurality of packets and determine whether a network failure occurs to generate a determination result according to the contents of the plurality of packets; and an alarm module, coupled to the packet filter module and configured to output an alarm signal to implement an alarm function according to the determination result; wherein the packet filter module detects time to live values of the plurality of packets from the contents of the plurality of packets and determines whether the network failure occurs according to the time to live values of the plurality of packets, and when detecting that a time to live value of a first packet of the plurality of packets is not decreased sequentially, the packet filter module determines that the network failure occurs and accordingly generates the determination result.

6. The network failure detection device of claim 5 , wherein the packet filter module analyzes the contents of the plurality of packets and detects whether the plurality of packets include more than one address of a dynamic host configuration protocol server, and when detecting that the plurality of packets include more than one address of the dynamic host configuration protocol server, the packet filter module determines that the network failure occurs and accordingly generates the determination result.

7. The network failure detection device of claim 6 , wherein the address of the dynamic host configuration protocol server is a physical address.

8. The network failure detection device of claim 5 , wherein when the determination result indicates that the network failure occurs, the alarm module outputs the alarm signal to implement the alarm function.